US3813489A - Low light television camera - Google Patents

Low light television camera Download PDF

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Publication number
US3813489A
US3813489A US00303554A US30355472A US3813489A US 3813489 A US3813489 A US 3813489A US 00303554 A US00303554 A US 00303554A US 30355472 A US30355472 A US 30355472A US 3813489 A US3813489 A US 3813489A
Authority
US
United States
Prior art keywords
target
television camera
phosphor
image intensifier
guard ring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00303554A
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English (en)
Inventor
M Bedgood
M Ramsay
W Barnes
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Standard Electric Corp
Original Assignee
International Standard Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Application granted granted Critical
Publication of US3813489A publication Critical patent/US3813489A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/26—Image pick-up tubes having an input of visible light and electric output
    • H01J31/28—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen
    • H01J31/34—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen having regulation of screen potential at cathode potential, e.g. orthicon
    • H01J31/38—Tubes with photoconductive screen, e.g. vidicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/26—Image pick-up tubes having an input of visible light and electric output
    • H01J31/28—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen
    • H01J31/34—Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen having regulation of screen potential at cathode potential, e.g. orthicon
    • H01J31/36—Tubes with image amplification section, e.g. image-orthicon
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/40—Circuit details for pick-up tubes

Definitions

  • the phosphor screen of an image intensifier fiberoptically coupled to the target of a television camera tube is connected to a point in the video amplifier which provides'a signal to decouple the target from ground.
  • the phosphor acts as a guard ring to avoid capacitive effects.
  • the feedback signal from the amplifier is equal in magnitude and phase to the voltage signal produced at the target.
  • An added guard ring may be connected to the same potential as the phosphor.
  • One of these techniques involves coupling the target capacitance and the input capacitance of the video amplifier with a small inductance to form a 'r r-filter.
  • This filter with proper adjustment of component values, canconsiderably extend the high frequency performance of the camera. Obviously such a filter could be redesigned to take account of the increased capacitance presented by the introduction of an image intensifier into close proximity with the target. The use of this technique will not however affect the problem of pick-up.
  • the other technique previously employed with television cameras not incorporating an image intensifier has involved the use of the guard ring principle.
  • the target of the-camera tube is encircled by a guard ring which is driven from a point in the video amplifier providing a signal voltage equal in magnitude and phase with the signal produced at the target.
  • the target is effectively decoupled from ground, the capacitance to ground of the target being replaced with what would be a larger capacitance between target and guard ring if it were not for the connection between these two integers.
  • the gain provided by an image intensifier depends upon the potential difference developed across it. Therefore since the phosphor potential is required to float it might be throught that the power supply for the image intensifier ought to be tied to this floating potential rather than being referred to ground. It is however now necessary to float the power supply because the normal fluctuations in potential of the target are very small compared withone volt, and therefore these fluctuations are quite insignificant in comparison with the normal operating potential across an image intensifier, which is typically 'in the range 5 45 kV, depending upon the number of stages. If however the power supply is grounded, the video amplifier must present a fairly low impedance to direct current because the current flowing through the image intensifier will also have to flow through the amplifier.
  • a low light level television camera including a video amplifier and a television camera tube having a photoconductive target fiber-optically coupled to the output phosphor of an image intensifier, wherein the phosphor is connected to a point in the video amplifier adapted to provide a voltage signal equal in magnitude and phase to the voltage signal produced at the target.
  • FIGURE schematically shows a-diagram of part of the camera circuit including'the image intensifier and power supply together with part of camera tube and the first part of the video amplifier.
  • a single stage image intensifier 1 having a photocathode 2 and a phosphor 3, is coupled by a fiber optical plate 3a to the.
  • photoconductive target 4 of a television camera tube 5 having a fiber-optic face plate 6.
  • the target 4 may be encircled by a guard ring 7, and a direct-electrical connection is made between this guard ring and the phosphor 3.
  • the photocathode 2 is held at a large negative potential by means of a voltage multiplier 8 powered by an oscillator 9.
  • the image intensifier may optionally be provided with a measure of automatic brightness control by arranging for the oscillator 9 to be fed from a current limiting supply.
  • the target of the camera is held at a negative potential by a target voltage supply (not shown) and the target signal output provided by scanning the target with an electron beam within the tube in a known manner is ac. coupled to an FET input amplifying stage 10 having a transistor load 11.
  • This amplifying stage is followed by a conventional transistor amplifying stage 12.
  • a proportion of the output of this second amplifying stage 12 is fed to the guard ring 7 and phosphor 3.
  • the output of the amplifying stage is in phase with the target signal output, and the values of the resistors 13 and 14 are chosen so that the magnitude of the proportion of this output which is fed to the guard ring and phosphor is equal to that of target signal output.
  • the circuitry described above is not substantially A changed if the single stage image intensifier is replaced by either a two stage or a three stage image intensifier.
  • the connections to intermediate photocathodes and phosphors in such, image intensifiers are made in the conventional way to intermediate points in the voltage multiplier.
  • the voltage multiplier has, of course, to be composed of more sections in order to provide the greater voltages required.
  • Automatic brightness control may be achieved in the same manner as described above of limiting the current input to the oscillator. Alternatively it may be achieved by methods substantially as described in U.S. Pat. No. 3,694,659, issued Sept. 26, I972 and assigned to the same assignee as the instant application, which rely upon monitoring the power dissipation in or current flow through the final stage of the image intensifier.
  • a low light level television camera system comprising a video amplifier, a television camera tube having a photoconductive target at one end connected to provide an output voltage signal to said video amplifier, an image intensifier tube having an output phosphor screen, and fiber optic means coupling said phosphor screen to said target, said phosphor screen being connected to a point in said video amplifier providing a feedback voltage signal equal in magnitude and phase to said output voltage signal from said target and being at a predetermined direct voltage with respect to a reference potential.
  • a guard ring is disposed around said camera tube adjacent said target and is connected to said point in said video amplifier providing said feedback voltage signal equal in magnitude and phase to said output voltage signal from said target, and said image intensifier output phosphor screen is at a fixed potential with respect to said camera tube target.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Transforming Light Signals Into Electric Signals (AREA)
US00303554A 1971-11-23 1972-11-03 Low light television camera Expired - Lifetime US3813489A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5429171 1971-11-23

Publications (1)

Publication Number Publication Date
US3813489A true US3813489A (en) 1974-05-28

Family

ID=10470535

Family Applications (1)

Application Number Title Priority Date Filing Date
US00303554A Expired - Lifetime US3813489A (en) 1971-11-23 1972-11-03 Low light television camera

Country Status (7)

Country Link
US (1) US3813489A (enExample)
JP (1) JPS5118769B2 (enExample)
DE (1) DE2257046A1 (enExample)
FR (1) FR2160997B1 (enExample)
GB (1) GB1345005A (enExample)
IT (1) IT971082B (enExample)
NL (1) NL7215541A (enExample)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4254437A (en) * 1978-06-29 1981-03-03 Proxitronic Funk Gmbh & Co. Kg Image intensifier attachment for attachment to the front lens of a television camera
US4550251A (en) * 1983-07-08 1985-10-29 Varian Associates, Inc. Image intensifier tube with increased contrast ratio
US5103301A (en) * 1988-03-25 1992-04-07 Alfonso Cosentino Sequential color television camera having image intensifier portion
US20050203238A1 (en) * 2004-03-01 2005-09-15 Haiying Zhou Tire compositions comprising surface-modified silica
WO2013043955A1 (en) 2011-09-23 2013-03-28 Ppg Industries Ohio, Inc. Treated fillers, compositions containing same, and articles prepared therefrom
WO2014209249A1 (en) 2013-06-27 2014-12-31 Miroshnychenko Sergii Compound fiber-optic connector and x-ray receiver based thereon
RU2554275C1 (ru) * 2014-03-20 2015-06-27 Открытое акционерное общество "Центральный научно-исследовательский институт "Электрон" Устройство на основе инфракрасного видикона

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5385354U (enExample) * 1976-12-15 1978-07-14
GB2160739A (en) * 1984-06-23 1985-12-24 Mclennan Marine Limited Night vision systems
CN103048663B (zh) * 2013-01-21 2014-08-06 南京恩瑞特实业有限公司 光学目标跟踪与监视综合电视系统

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3341655A (en) * 1964-03-23 1967-09-12 Rca Corp Transistorized preamplifier for television cameras

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3341655A (en) * 1964-03-23 1967-09-12 Rca Corp Transistorized preamplifier for television cameras

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4254437A (en) * 1978-06-29 1981-03-03 Proxitronic Funk Gmbh & Co. Kg Image intensifier attachment for attachment to the front lens of a television camera
US4550251A (en) * 1983-07-08 1985-10-29 Varian Associates, Inc. Image intensifier tube with increased contrast ratio
US5103301A (en) * 1988-03-25 1992-04-07 Alfonso Cosentino Sequential color television camera having image intensifier portion
US20050203238A1 (en) * 2004-03-01 2005-09-15 Haiying Zhou Tire compositions comprising surface-modified silica
US7259204B2 (en) 2004-03-01 2007-08-21 Bridgestone Corporation Tire compositions comprising surface-modified silica
WO2013043955A1 (en) 2011-09-23 2013-03-28 Ppg Industries Ohio, Inc. Treated fillers, compositions containing same, and articles prepared therefrom
WO2014209249A1 (en) 2013-06-27 2014-12-31 Miroshnychenko Sergii Compound fiber-optic connector and x-ray receiver based thereon
RU2554275C1 (ru) * 2014-03-20 2015-06-27 Открытое акционерное общество "Центральный научно-исследовательский институт "Электрон" Устройство на основе инфракрасного видикона

Also Published As

Publication number Publication date
DE2257046A1 (de) 1973-05-24
IT971082B (it) 1974-04-30
GB1345005A (en) 1974-01-30
FR2160997A1 (enExample) 1973-07-06
FR2160997B1 (enExample) 1976-06-04
JPS4860816A (enExample) 1973-08-25
JPS5118769B2 (enExample) 1976-06-12
NL7215541A (enExample) 1973-05-25

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